The invention relates to a crosslink over-center door hinge having a supporting wall member and a door member which are joined together by a crosslink mechanism formed by two linkage arms journaled together in their middle area, one end of each linkage arm being journaled directly on the supporting wall member or the door member, as the case may be, while the other end is coupled to the other member in such a manner that it is guided on a curve in space, and the coupling of the door end of the linkage arm that is journaled directly on the supporting wall member to the door member being accomplished by a link journaled on the door member at one end and on the linkage arm on the other, while the cabinet-internal end of the linkage arm directly journaled on the door member is coupled to the supporting wall member either by a frictional guidance of the linkage arm on the supporting wall member or indirectly by an interposed link, and having an over-center or snap-action mechanism provided with a closing spring, which resiliently forces the hinge to its end position at least when it is closed to the closed position.
Crosslink hinges are used in modern furniture construction whenever the desired door opening and closing movement cannot be achieved with the simpler and therefore less expensive four-joint hinges. Thus, for example, it is not possible with four-link hinges to achieve opening angles of much more than 105.degree. and 110.degree., and therefore the hinges which have to open to 180.degree. are today mostly constructed in the form of crosslink hinges. Even in the case of doors to be opened to less than 180.degree., the use of crosslink hinges may be necessary if the door to be mounted has to perform upon opening a relatively great component of movement out of the cabinet interior while remaining in front of the cabinet carcass. This is the case, for example, in certain recessed doors in which the thickness of the door leaf is relatively great. Crosslink hinges for 180.degree. opening angle are known, in which an over-center mechanism is incorporated which in the vicinity of the closed position forces the hinge to the end position. This over-center mechanism is formed, in a known crosslink hinge (German Offenlegungsschrift No. 2,552,729) for example by a pusher disposed for longitudinal displacement within one link arm, the pusher being biased by a spring, in the vicinity of the closed position, against a cam formed on on the door-related hinge member. The reaction force thus produced exercises the desired thrust in the closing direction.
This over-center mechanism operates satisfactorily, but when the door is opened the relatively large cam projecting from the cabinet becomes visible, and this is considered to be to some extent unsightly. In another known cross-link over-center hinge (German Petty Patent No. 7,510,753), there is provided in one linkage arm a spring-biased rocker arm whose one end has a recess which, when the closed position is approached, engages a transverse pin in a link coupled to this linkage arm and, as the closing movement continues, is forced beyond a dead center position into a locking position. This over-center mechanism has the disadvantage that, when the hinge is open, the rocker arm can be shifted to the locking position by tampering. When an attempt is then made to close the door, the transverse pin does not enter into the recess in the rocker arm but strikes against the outside of the rocker arm. The over-center action then does not take place and the door cannot be fully closed.